One type of popular supplement may be doing more harm than good

Navigating the murky waters of supplements is no easy task, even with about half of all Americans taking some form of vitamins or minerals in pill form.

Fish-oil pills, which deliver omega-3 fatty acids that can have a blood-thinning effect, made about $1 billion in sales in 2012. A Frontline investigation released Tuesday looked into what actually goes into fish oils and if those fish oils are actually doing what we think they do.

The short answer: It might be better to get your omega-3 fatty acids directly from fish than from a pill.

But the data it takes to arrive at this answer can get complicated. For one thing, it’s hard to know what you’re getting from the pills in terms of quality.

By global fish oil trade association GOED’s standards, about 20% of the 47 versions of fish oil pills from New Zealand aren’t up to industry standards for how intact the lipids, or fats, in the pills are, a spokesman for the organisation told Frontline. Fish oil is fairly sensitive, which means it can break down pretty easily into a form that’s not helpful. But other studies have arrived at different conclusions — a different New Zealand-based study of the same types of pills found that roughly 83% were not of OK quality.

Despite these quality issues, there’s also evidence that the supplements themselves — even those that are high-quality — won’t necessarily do the things they claim to do.

“For cardiovascular disease, one has to say there is no compelling evidence that taking fish oils protects against the first heart attack or a second heart attack,” Dr. Andrew Grey, one of the authors of the study told Frontline.

But looking at much of the same evidence, the fish oil trade association didn’t come to the same conclusion.

“I think what you’re looking at are the abstracts,” Adam Ismail, GOED spokesman, told Frontline. “Those papers are looking at large areas of cardiovascular disease. I think it’s hard to argue that omega-3s aren’t important for how your heart functions.”